This invention relates to a superconductive composite material useful as a superconductive magnet, etc. and a method of producing such a composite material.
JP-A-7-111213 discloses a superconductive magnet using a bulk of a superconductive metal oxide REBa.sub.2 Cu.sub.3 O.sub.7-.delta. (RE: a rare earth element; .delta.: a number representing an oxygen deficiency; this metal oxide is also shown as RE--Ba--Cu--O) containing pinning centers capable of trapping a magnetic field. FIG. 10 shows Jc-B curves of bulks of Y123 and Nd123. These bulks are square plates having a size of 20.times.20.times.2 (cm) as shown in FIG. 9 and show the critical current density as shown in FIGS. 11 and 12. The trapped magnetic field distribution at a position spaced apart by 12 cm from the surface of the bulk is shown in FIGS. 13 and 14, from which it will be understood that a strong magnetic field is not obtainable in the case of the bulks of Y123 and Nd123 having a structure shown in FIG. 9.